My 22 year old grandfather just after Belgium was liberated in WW2. But what is the bike? Anybody who know?

https://i.redd.it/uhpafkwje4t11.jpg via /r/motorcycles https://www.reddit.com/r/motorcycles/comments/9pilir/my_22_year_old_grandfather_just_after_belgium_was/?utm_source=ifttt